Immune Checkpoint Inhibitors-Associated Myocarditis: Diagnosis, Treatment and Current Status on Rechallenge

Immune checkpoint molecules like cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed cell death 1 (PD-1) or its ligand, programmed cell death ligand 1 (PD-L1), play a critical role in regulating the immune response, and immune checkpoint inhibitors (ICIs) targeting these checkpoints have shown clinical efficacy in cancer treatment; however, their use is associated with immune-related adverse events (irAEs), including cardiac complications. The prevalence of cardiac irAEs, particularly myocarditis, is relatively low, but they can become a severe and potentially life-threatening condition, usually occurring shortly after initiating ICI treatment; moreover, diagnosing ICI-related myocarditis can be challenging. Diagnostic tools include serum cardiac biomarkers, electrocardiography (ECG), echocardiography, cardiac magnetic resonance (CMR) and endomyocardial biopsy (EMB). The treatment of ICI-induced myocarditis involves high-dose corticosteroids, which have been shown to reduce the risk of major adverse cardiac events (MACE). In refractory cases, second-line immunosuppressive drugs may be considered, although their effectiveness is based on limited data. The mortality rates of ICI-induced myocarditis, particularly in severe cases, are high (38-46%). Therapy rechallenge after myocarditis is associated with a risk of recurrence and severe complications. The decision to rechallenge should be made on a case-by-case basis, involving a multidisciplinary team of cardiologists and oncologists. Further research and guidance are needed to optimize the management of cancer patients who have experienced such complications, evaluating the risks and benefits of therapy rechallenge. The purpose of this review is to summarize the available evidence on cardiovascular complications from ICI therapy, with a particular focus on myocarditis and, specifically, the rechallenge of immunotherapy after a cardiac adverse event.